1. Field of the Invention
The present invention relates generally to a medical instrument for use with a surgical ligation clip applicator. More particularly, the invention is directed to a unitary single-fire module for housing a two-part ligation clip for securing and closing the two-part ligation clip around a vessel to be occluded.
2. Prior Art
A surgical ligation clip is used to compress a severed blood vessel to stop the flow of blood. The single-fire module of the subject invention is particularly designed for housing and applying a two-part surgical ligation clip. The first part comprises generally a Y-shaped clamp or track having two extended arms for fitting around a vessel to be ligated. The second part is a U-shaped clip body with an extended slot for slidably engaging the track and closing the arms of the clip track about the vessel. Ligation clips of this type are disclosed in U.S. Pat. No. 4,590,937 and in U.S. Pat. No. 5,306,283, both of which are assigned to the assignee of the subject invention and are incorporated herein by reference.
There are many types of known modules for use with mechanical applicators for closing a conventional ligation clip around a vessel. The module can be attached to the distal end of the mechanical applicator by a spring loaded latch as disclosed in U.S. Pat. No. 5,354,304 or other type of latching means which attachably secures the module to the applicator. Several examples of other known applicators include the so-called push-pull type, which uses a plunger or a piston, or a fulcrum type applicator having scissors-like or pliers-like handle. U.S. Pat. No. 5,354,304 discloses a preferred single-fire mechanical applicator for use with the subject invention and is incorporated herein by reference.
U.S. Pat. No. 5,354,304 further discloses a prior art single-fire module for housing the two-part ligation clip prior to application. The prior art module holds the clip track of the ligation clip in a stationary position as an advancing pusher at the proximal end of the module moves the sliding clip body of the ligation clip forward in order to compress the clip track around a vessel of a patient. The prior art module comprises two substantially identical cartridge halves that are joined together by integral alignment pins that align the two halves together so that the two halves may be welded securely together during manufacturing. Upper and lower metal latches, each having an integral spring and opposing trunions, are housed inside the middle portion of the module and pivot in holes formed in each cartridge halve. The integral springs press against ribs also formed inside each cartridge halve and urge the proximal ends of the metal latches toward each other so that the metal latches are compressively housed inside the module. A prior art pusher is also provided at a proximal end opening of the module for actuating the two-part ligation clip when the applicator is actuated by the user. The latches are also provided with a V-shaped end portion which engages opposing grooves formed on either side of the prior art pusher for retaining the pusher inside the cartridge housing.
Although the above prior art module provides an efficient and advantageous means of occluding a vessel with a two-part ligation clip, several disadvantages remain. The prior art module is costly to manufacture because of the different parts that must be manufactured and put together during assembly. Specifically, the metal latches with their cantilevered compression springs are costly to manufacture and time-consuming to assemble into the prior module since this must be done manually. Further, the prior art module can tend to jam due to the metal latches being improperly assembled or defects that occur during manufacturing of the metal latches. Finally, the prior art module has a wide profile along its longitudinal axis which may block or interfere with the user's view of the vessel during application of the two-part clip, with the applicator.
There therefore exists a need in the art for a unitary single-piece module for housing and applying a ligation clip in which the module is of a single unitary design with no separate parts therein. There also exists a need in the art for a single-piece module that is less costly to manufacture and requires little or no assembly during manufacturing. Finally, there also exists a need for a single-piece module housing having a low profile that permits clearer viewing of a vessel during ligation.